1. Field
Example embodiments relate to an organic light emitting display, and more particularly, to an organic light emitting display having an oxide thin film transistor and a fabricating method thereof.
2. Description of the Related Art
An organic light emitting display is a next generation display having self light emitting characteristics and superior display characteristics, e.g., viewing angle, contrast, response speed, power consumption, and the like, as compared, e.g., to a liquid crystal display (LCD).
The organic light emitting display may include an organic light emitting diode (OLED) having an anode electrode, an organic thin film, and a cathode electrode. The organic light emitting display may be classified as a passive matrix type, i.e., in which the OLEDs are connected to each other between scan lines and signal lines by a matrix method to form pixels, or as an active matrix type, i.e., in which respective pixels are controlled by a thin film transistor (TFT) serving as a switch.
In general, the TFT used in the active matrix type organic light emitting display may include an active layer for providing a channel region, a source region, and a drain region, and a gate electrode formed on the channel region, and may be electrically insulated from the active layer by a gate insulation layer. Such an active layer of the TFT may be generally formed of a semiconductor layer, e.g., an amorphous silicon layer or a poly-silicon layer.
However, when the active layer is formed of amorphous silicon, mobility may be low. Therefore, it may be difficult to implement a driving circuit driven at high speed.
When the active layer is formed of poly-silicon, while mobility may be increased, e.g., as compared to amorphous silicon, a threshold voltage may be not uniform. Therefore, a compensation circuit for compensating distribution of the threshold voltage and the mobility may be needed. However, since an active layer formed of poly-silicon may require a complicated compensation circuit with a plurality of TFTs and capacitors, yield may be low and a resultant planar structure thereof may increase a number of masks used during fabrication thereof, e.g., as compared to a TFT having an active layer of amorphous silicon, so that fabricating costs may increase. Further, a conventional TFT fabricating method using low temperature poly-silicon (LTPS) may have a difficulty to be applied to a large substrate due to required high processing costs, e.g., laser heat treatment, and difficult control thereof.